here are many ways one would like to have seen the playwright Joe Orton die. Heart attack following a particularly severe fit of the giggles, for instance. Or suffocation by his great aunt's bloomers. But having an axe driven through his skull by his lover and mentor, the failed playwright Kenneth Halliwell, was a rude departure.

Some would say Orton had it coming. This irreverent pair were too involved with each other professionally and emotionally, too similar in aspirations, too similar in age. Orton was more talented than Halliwell, making Halliwell, jealous and unstable by nature, an unsuitable mentor.

The Orton tragedy is a rare, and extreme, example of what happens when the mentor-mentee relationship, traditionally intended to bring out the potential of a younger person by someone older and wiser, goes out of control.

Less notorious and rather more celebratory mentoring relationships abound, kicking off with the sage Mentor's guiding of Odysseus on his trip back from Troy and tripping through the centuries from Mozart and his father Leopold in the 18th century, through Brahms and Schumann in the 19th, to the chefs Michael Caines and Albert Roux, the tennis champion Boris Becker and his coach Brevska, and the bands the Happy Mondays and Oasis in the 20th.

John Radford, emeritus professor of psychology at East London University, one of several universities using a mentoring scheme between third and first year undergraduates, has studied the nature of talent for several years. He says a mentor is vital if talent is to flourish. "A mentor brings out the best in someone, often ensuring that their innate talent realises its full potential." A mentor gets that light up and out from under its bushel.

Traditionally associated with the arts and sport, and the basis of Oxford and Cambridge's tutoring system, the philosophy behind mentoring has recently become popular in the corporate realm. Many companies - Marks & Spencer, Reuters, Virgin, for example - now recognise the value of one- to-one relationships in what are otherwise large, impersonal and competitive environments. Schemes run on a formal and informal basis. "It is very much the way Virgin has developed over the years," explains Will Whitehorn, the company's corporate affairs director. Though the term "mentoring" is not used, employees are brought in within senior management as "executive assistants" to one of the corporation's high flyers. "It is intended that you grow and learn and experience the business, that you become an entrepreneur," says Whitehorn.

Whitehorn, for example, joined the company as executive assistant to a senior PR executive. Within a matter of years he was sitting on the board. "The idea is to make the company grow organically and to grow the skills of people. We just need good people and you don't get them unless you take an interest in what they are doing."

For Joanna Moore (not her real name), a former marketing trainee at Reuters, the benefits were two-fold, easing not only mobility within the company but sexual politics also. The mentoring scheme was very informal, however, and management trainees were expected to select their own mentor, which was not always successful.

"The organisation was male-led and quite traditional, such that it was open to suggestion that young female sales trainees had got on well because they had slept with somebody," recalls Joanna. "The existence of mentoring meant that you could go out and have drinks with senior male colleagues without something being read into it. If somebody said, 'Oh, you get on very well with James,' for instance, you could explain it by replying, 'Well, actually he is my mentor'."

Choice of mentor was open to misinterpretation, however. When Joanna finally chose to ask a senior figure whom she had already got to know, she was taken aback when he refused. "It was well known that he was a great womaniser. I didn't think this would matter, but he was worried that any future progress I might make within the company, particularly if I did well very quickly, would be attributed to this."

The mentor who has not just their libido but self-gain, money or fame at heart, is also a bad mentor. Pushy and often unfulfilled parents are frequent offenders. According to Michael Howe, professor of psychology at Exeter University, they are also the most worrying. "Parents who identify with their child's success and live through it vicariously are the most potentially dangerous of mentors." Witness the tennis player Mary Pierce's overbearing father. "The parent does not let the child become independent. Conflict is at its most severe in parents who are determined to turn their children into geniuses."

Not an easy task, particularly if your child's so-called genius or startling talent rests on their precocity and youth. Enter, and exit, Shirley Temple. But if innate talent is there, conflict is less likely to surface between parents and offspring, as the relationships between child mathematician Ganesh Sittampalam, who gained a first-class degree in maths aged 13, John Adams and Ruth Lawrence and their fathers testify.

Among artists, mentoring is often more instinctive and certainly less self-interested. The conductor Sir Simon Rattle, for example, was compelled by the genius he identified in his protege Daniel Harding, after watching him conduct a complicated Schoenberg piece at music school when a teenager. "He was doing the piece a few months later," recalls Daniel, "and he asked me if I would like to come down and listen to rehearsals and maybe he'd give me a chance to do some conducting." The relationship went from there.

Rattle had nothing to gain except a vicarious pleasure in Harding's success and the satisfaction of joining a long musical tradition of mentoring. The historical absence of an equivalent tradition among female artists is one of the forces that drew together the artists Paula Rego, whose belief in the power of women is so disarmingly conveyed in her paintings, and Laura Godfrey Isaacs. Like so many mentees, what Harding and Godfrey Isaacs have found so precious, apart from the technical advice they have been given, is the knowledge that their mentors have been there before and have survived. It also takes the edge off the loneliness that haunts so many artists.

"Simon is about the only person I know who knows what it's like to be a conductor at 20, and the problems and complications that come with that," says Harding. "The kind of support, encouragement and advice he can give me is totally unique and invaluable. When he was in that position there were many people to offer him help and advice but there was no one who had been through it themselves. Most importantly, I can see that he went through all this shit himself and he did all right."

Fashion designers are as well known as musicians for taking on proteges. Vivienne Westwood's bustles may not appear in Bella Freud's restrained lines, but that they are cut out of the same cloth is undisputed. But what many so-called fashion gurus are actually doing is making a commercial pact with a young designer: you come to work for my famous house, I benefit from your hard graft and you benefit from my name.

That is what happened when Reynold Pearce, described as a protege of Galliano's, went to work for this fashion icon. But Pearce has never considered Galliano a mentor or role model.

"I'd wanted to work at his studio for years, ever since I started studying fashion," he says. "But I wasn't expecting anybody to sing my praises or to be taught. In fashion you are just there to knuckle down and get on with the job. It is just a learning process, an experience, nothing to do with encouragement, although Galliano was always around and always charming.

"I watched how he progressed and obviously I always thought St Martins was the school to go to. I watched the fairy story, the way he was picked up by Browns. But that is more like a dream rather than something you are going to form your life plan around."

It was the unquestioning support of his mother and father, a fashion fabric technician and scientist respectively, that encouraged Pearce's potential. "My parents were encouraging in everything, whatever we wanted to do," says Pearce. "It was nothing to do with being pushed in one direction or another. At an early stage people used to commend me on my art work, but I ended up dropping art and doing sciences up to A- level. When I chose to do fashion my mother did say, 'Now you do realise this is a damn difficult career choice you're making'. She always says how she warned me."